Subtask 1 - Interactive map of survey entries

Create an interactive leaflet map divided by inputstates that are colored in relation to a total number of survey responses across all waves, following good practice of visualization. For this plot, you should:

• employ a color palette based on the number range of survey entries.

• use the OpenStreetMap.Mapnik provider tile.

• create a popup that reads “Total survey responses for {inputstate initials}: {Number}”.

• add a color legend with a title.


Load data

survey_data <- readRDS("./survey/meof_usa_survey_df.rds")
survey_data <- haven::as_factor(survey_data)

Get geodata for US

# get geodata for the US state we are interested into
states_sf <- tigris::states(cb = TRUE, class = "sf")

Get number of responses for each each state

# filter the rows in the states_sf data frame based on whether the values in the 
# "NAME" column are present in the unique_states vector (matching state_sf with unique_States)
unique_states <- unique(survey_data$inputstate)
states_sf <- states_sf[states_sf$NAME %in% unique_states, ] 

# get the number of responses for each state
survey_data_map <- survey_data |> 
  group_by(inputstate) |> 
  summarize(num_responses = n()) # assuming that each row is a unique response

# check if the number of responses match:
# sum(survey_data_map$num_responses)
# the number should be equal to the number of observations in the original dataset,
#  and it is: both are 10200 (number of rows).

Add percentages

# add percentage of responses to the survey_data_map
total_responses <- sum(survey_data_map$num_responses)
survey_data_map <- survey_data_map |> 
  mutate(percentage = round((num_responses / total_responses) * 100, 2))

# join map data with spatial data (including percentages)
map_df <- left_join(states_sf, survey_data_map, by = c("NAME" = "inputstate"))
map_df <- st_transform(map_df, crs = 4326) # solve warning

Create map

# create a color palette function based on the range of num_responses
max <- max(map_df$num_responses)
min <- min(map_df$num_responses)

bins <- c(min, 20, 50, 100, 200, 400, 600, 800, max)
pal <- colorBin("YlGn", domain = map_df$num_responses, bins = bins)

# Create the leaflet map
map <- leaflet(map_df) %>% 
  setView(lng = -95.7129, lat = 37.0902, zoom = 2.5) %>% 
  addProviderTiles(providers$OpenStreetMap.Mapnik) %>% 
  addPolygons(
    fillColor = ~pal(num_responses),
    weight = 0.8,
    opacity = 2,
    color = "lightgrey",
    dashArray = "NULL",
    fillOpacity = 0.7,
    popup = ~paste("Total survey responses for", NAME, ":", num_responses, 
                   "<br>Percentage of Total:", sprintf("%.2f%%", percentage))) |> 
  addLegend(
    pal = pal, 
    values = ~num_responses, 
    opacity = 0.7, 
    title = "Number of Responses",
    position = "bottomright")

Visualize map